Plastic, Steel Pack of 2: Students spend hours in the classroom and require comfortable classroom chairs to hold their attention during lesson plans. These shell back stack chairs were designed to promote healthy sitting habits. Student stack chair stacks up to 12 chairs high High density polypropylene comfort-molded seat shell with UV, heat and cold protection Non-corrosive chrome plated frame finish, 18 gauge steel frame, self-leveling floor glides PRODUCT MEASUREMENTS: Overall Size: 20"W x 18.25"D x 28.75"H; Seat Size: 15.5"W x 14"D x 16"H; Back Size: 15"W x 13.5"H